The amount of juice that is in one lime is around 2 tablespoons.
Although the actual amount of juice that is in the one lime will depend on the size of the lime and the ripeness of the lime.
However juice of one lime is often considered to be around 1 ounce or 30 ml of juice per lime.
Smaller limes will yield less juice than larger limes.
Small limes often yield 1 tablespoon of lime juice.
Medium size limes often yield around 1.5 to 2 tablespoons of lime juice.
And large size limes often yield around 3 tablespoons of lime juice.
And so if a recipe calls for the juice of 1 lime that most often equals to 1 oz or 30 ml of lime juice.
You can also substitute bottled lime juice for fresh lime juice as well although fresh lime juice tends to yield better results with the recipe.
If you don't have lime juice, you can also substitute lemon juice for a similar citrus flavor, or vinegar for acidity.
Although you might have to adjust the amount of vinegar or lemon juice to your taste.
Orange juice, grapefruit juice or even verjuice can also be used as a substitute for lime juice for a milder citrus flavor or even use citric acid powder if you want or need pure acidity.
And if you prefer a more unique twist you can use pomegranate molasses, tamarind paste even a dollop of some sour cream.